How to interface with a pcb

Discussion in 'Embedded Systems and Microcontrollers' started by smurfy333, Oct 18, 2015.

  1. smurfy333

    Thread Starter New Member

    Oct 18, 2015
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    Hello all

    How do I interface with a PCB when there is no serial connection, so here is the background, I have a tumble dryer which has annoying programming, when the cycle has finished it stop for 30?seconds a red light flashes telling you the cycle has finished then starts up again and carries on doing the same thing until you open the door to stop the cycle, what I want to do is re-program so when it stop initially for it to stop and not carry on, not only to s my wife bending my ear about it, it wastes electricity and it's very annoying, I can post a pic of the PCB if needed.
     
  2. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    I know the feature you mean. It is to prevent wrinkles. It is annoying.

    Without having accessing to the "PCB" or having full technical details on said "PCB" there is no way anyone is going to be able to help.

    Most of the MCUs in these devices are not programmable anyway.

    What you could do is to build a circuit that senses when the motor goes from on to off, it would trip a relay to keep the motor off. The only problem with that is that you would to need to reset it when you want to use it again.

    ill probably be easier to find a dryer that lets you disable that feature.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    @smurfy333

    All you need is access to the plunger switch in the door. When a microphone on your microcontroller detects the annoying beep, (or an input pin detects power to the annoying beeper), have your relay briefly short the switch on the door plunger to make the master MCU think the door was opened one time (which makes the dryer stop beeping).
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
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    The firmware is probably on a OTP chip - you may not be able to do anything about it.

    The absolute easiest way is to use a timer switch to cut the mains at "times up".

    There are commercial timers in a plug-top format, but they're usually for cycling lights to make burglars think someone is in - they probably can't handle heavy loads like a tumble drier.

    With the DIY route, you can make a count down timer that does exactly what you want it to do. You'll need some care to make sure the relay/SSR/triac you select can handle the load with a decent safety margin.
     
  5. smurfy333

    Thread Starter New Member

    Oct 18, 2015
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    Here is a pic of it helps
     
  6. MikeML

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    Oct 2, 2009
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    What's wrong with training the wife to get out of her TV chair, and take the clothes out of the dryer when the cycle is done?
     
  7. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Not really.

    Gopher offered a good suggestion. Mike offered an even better suggestion though I am not sure I understand the TV chair part. ;)
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
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    Probably better than hacking the controller board - detect some event to drop out a contactor and cut the mains.

    If the dryer draws high current for the whole cycle and then idles before starting over, a current solenoid could do the trick. But you'd have to have a start button that bypasses the contactor while you set it going.

    If it beeps at the end of the cycle - simply couple out the signal to the sounder.
     
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